Questions

[hhsting]

1 . NEC 2014 section 250.80 says grounded system conductor. Is that neutral? Any definition in Article 100? I see grounded conductor but don’t see grounded system conductor

2. NEC 2014 section 250.80 says metal enclosures and raceways for service conductors and equipment... does metal enclosure and raceway for service conductors and equipment include service trough with service conductors in it on line side of service discos?

 

[hhsting]

I tried searching own my own but I was not able to find anything. Sorry for my ignorance but is grounded conductor same as grounded system conductor or they are two different items? Where is my buddy Electrofelon?

 

[augie47]

Likely he's burnt out from sting questions most here are.
Grounded conductors are not necessarily neutrals.
service"troughs" would be considered raceways,

 

[LarryFine]

Yes to all.

The supply neutral is basically the neutral conductor and the raceways enclosing them.

The premises equipment grounding system doesn't begin until the main disconnect.

A grounded system is one with an intentionally-grounded conductor.

A neutral is usually, but not always the conductor grounded when one is.

And, as Augie said, not every intentionally-grounded grounded conductor is a neutral.

 

[LarryFine]

I wish I had all of your knowledge and expertise, experiences. I do apologize for my ignorance.

If you did, you'd be answering questions instead of asking them.

I believe we enjoy teaching, and you have nothing to apologize for.

After all, you're wise enough to ask, and to know where to go to ask.

If you ever feel like talking, PM me for my phone number. I'm up late.

 

[hhsting]

Yes to all.

The supply neutral is basically the neutral conductor and the raceways enclosing them.

The premises equipment grounding system doesn't begin until the main disconnect.

A grounded system is one with an intentionally-grounded conductor.

A neutral is usually, but not always the conductor grounded when one is.

And, as Augie said, not every intentionally-grounded grounded conductor is a neutral.

Oh okay. So grounded system conductor that’s mentioned in NEC 2014 section 250.80 same as grounded conductor mentioned in definition NEC 2014 section 100 or they are different?

 

[electrofelon]

1 . NEC 2014 section 250.80 says grounded system conductor. Is that neutral? Any definition in Article 100? I see grounded conductor but don’t see grounded system conductor

2. NEC 2014 section 250.80 says metal enclosures and raceways for service conductors and equipment... does metal enclosure and raceway for service conductors and equipment include service trough with service conductors in it on line side of service discos?

I don't blame you for being confused. It is a bit odd they use the word "system" in 250.80. I dont really see that it is necessary and can add confusion.

 

[Carultch]

Oh okay. So grounded system conductor that’s mentioned in NEC 2014 section 250.80 same as grounded conductor mentioned in definition NEC 2014 section 100 or they are different?

"Grounded conductor" or "grounded system conductor", note the "-ed" ending of "grounded", means the conductor that is intentionally at the same voltage as ground, and set up for carrying current under normal conditions. It is most common that this is also the neutral.

An example of where a grounded conductor is not a neutral, is the phase that is grounded on a corner-grounded delta system.
Another more common example where a grounded conductor is not technically a neutral, is the grounded polarity in a 2-wire DC system. People may call it a neutral anyway, and most of us still understand what you mean.
An example of where a neutral conductor is not a grounded conductor, is the neutral in a floating WYE system where all three phases and the neutral are isolated from the EGC and housing.

The reason for the examples where the grounded conductor is not considered a neutral by strict definition, is that neutral is defined to either be at the center of all the phases, or centered between two of them (as in a high leg delta system).

The term raceway, means that it is a physical pathway for wiring that is completely enclosed. This is the general term that is inclusive of all conduit, tubing, wireways, wire troughs, and surface raceways. Pull/junction boxes would be included in the concept of the raceway system. A cable tray or messenger wire would be a wiring method, but would not be a raceway.

 

[hhsting]

So what I have is installation where incoming electric utility service conductors go into POCO service box which then go into service trough and from trough connected to each of four service disconnects with different sizes.

In the POCO service box their is neutral to ground bonding jumper which is brought from POCO service box along with the neutral into service trough. From trough the neutral, bonding jumper and phase conductors total of 5 conductors are brought to each individual service disconnects. Their is main bonding jumper in each service disco but the bonding jumper is brought in equipment grounding conductor bus bar and neutral to neutral bus bar. The service trough is where the main grounding electrode system is located.

Assume neutral is grounded at the utility transformer it’s 480V/277V wye grounded system so neutral is the grounded conductor.

According to 250.80 and 250.92 should their be this bonding jumper from POCO service box or everything bonded and grounded thru neutral only in above scenario?

 

[LarryFine]

According to 250.80 and 250.92 should their be this bonding jumper from POCO service box or everything bonded and grounded thru neutral only in above scenario?

When I said:

The supply neutral is basically the neutral conductor and the raceways enclosing them.

What I meant was that the service neutral and raceways/enclosures are, despite our teachings, in parallel. There is no separate EGC until the point where the last neutral bonding point and the electrode conductor terminations are.

 

[electrofelon]

So what I have is installation where incoming electric utility service conductors go into POCO service box which then go into service trough and from trough connected to each of four service disconnects with different sizes.

In the POCO service box their is neutral to ground bonding jumper which is brought from POCO service box along with the neutral into service trough. From trough the neutral, bonding jumper and phase conductors total of 5 conductors are brought to each individual service disconnects. Their is main bonding jumper in each service disco but the bonding jumper is brought in equipment grounding conductor bus bar and neutral to neutral bus bar. The service trough is where the main grounding electrode system is located.

Assume neutral is grounded at the utility transformer it’s 480V/277V wye grounded system so neutral is the grounded conductor.

According to 250.80 and 250.92 should their be this bonding jumper from POCO service box or everything bonded and grounded thru neutral only in above scenario?

This sounds OK to me. Only question is, that bonding jumper that comes from the POCO box, you said that goes into trough and into each service disconnect. How does it split from 1 into several? Is there a terminal bar in the trough that the incoming and outgoing bonding jumpers and the GEC land on? Just want to be clear on that, but it sounds ok.

Basically you can do 3 things to ground/bond service stuff:

1. Hit it with the grounded conductor (usually this is the neutral)
2. Hit it with a bonding jumper that connects to the grounded conductor somewhere else.
3. Bond it to something else that meets #1 or #2 thru acceptable fittings such as those in 250.92(B) 2,3,4.

A common problem with #1 is when you have parallel conductors or multiiple sets, its a bit of a chore to tap all the grounded conductors and bond them to the trough, box or whatever you are trying to bond. Usually in this case it is best to mount a terminal bar to the box or trough to accomplish this. IIRC there is a picture showing this method in the NEC handbook.

There are many different scenarios of course, but I generally go in reverse order as I listed them: Use things such as bonding type locknuts to bond everything together thus reducing the amount of things that need jumpers, and then use #2 to run a bonding jumper to a convenient place to grab the grounded conductor such as the service equipment since this will have a terminal bar.